Non-collinear 2k antiferromagnetism in the Zintl semiconductor Eu${}_5$In${}_2$Sb${}_6$

Abstract

Eu${}_5$In${}_2$Sb${}_6$ is an orthorhombic non-symmorphic small band gap semiconductor with three distinct Eu${}^{2+}$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances of known stoichiometric antiferromagnets and belongs to a family of Zintl materials that may host an axion insulator. Using single crystal neutron diffraction, we show that the $T_{N1}=14\mathrm{K}$ second-order phase transition is associated with long-range antiferromagnetic order within the chemical unit cell $\left(k_1=(000)\right)$. Upon cooling below $T_{N1}$, the relative sublattice magnetizations of this structure vary until a second-order phase transition at $T_{N2}=7\mathrm{K}$ that doubles the unit cell along the $\hat{c}$ axis $\left(k_2=\left(00\frac{1}{2}\right)\right)$. We show the anisotropic susceptibility and our magnetic neutron diffraction data are consistent with magnetic structures described by the ${\Gamma }_3$ irreducible representation with the staggered magnetization of the $k_1$ and $k_2$ components polarized along the $\hat{b}$ and $\hat{a}$ axis, respectively. As the $k_2$ component develops, the amplitude of the $k_1$ component is reduced, which indicates a 2k non-collinear magnetic structure. Density functional theory is used to calculate the energies of these magnetic structures and to show the $k_1$ phase is a metal so $T_{N1}$ is a rare example of a unit-cell-preserving second-order phase transition from a paramagnetic semiconductor to an antiferromagnetic metal. DFT indicates the transition at $T_{N2}$ to a doubled unit cell reduces the carrier density of the metal, which is consistent with resistivity data.

13 pages, 9 figures

References in corpus (8)

• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Colossal Magnetoresistance without Mixed Valence in a Layered Phosphide Crystal
• Spin order and dynamics in the diamond-lattice Heisenberg antiferromagnets CuRh2O4 and CoRh2O4
• Anisotropy of the magnetic and transport properties in EuZn${}_2$As${}_2$
• Engineering magnetic topological insulators in Eu${}_5{M}_2{X}_6$ Zintls
• Magnetic and electronic properties of Eu${}_5$In${}_2$Sb${}_6$
• Colossal piezoresistance in narrow-gap Eu5In2Sb6
• Surface and electronic structure at atomic length scales of the non-symmorphic antiferromagnet Eu${}_5$In${}_2$Sb${}_6$

Cited by in corpus (2)

• Hybrid-order topology in unconventional magnets of Eu-based Zintl compounds with surface-dependent quantum geometry
• Thermodynamic evidence for polaron stabilization inside the antiferromagnetic order of Eu${}_5$In${}_2$Sb${}_6$